Juan Meléndez

UWB Staircase-Profile Printed Monopole Design

In printed monopoles, the current distribution along the lower monopole sheet and upper groundplane edges can be made analogous to a transmission line distribution by an appropriate antenna feed design. Accordingly, the VSWR < 2 impedance bandwidth upper frequency limit can be estimated for staircase-profile printed 2D ultrawideband (UWB) monopoles. Following this guideline, three tailored-bandwidth prototypes are designed, implemented and measured. They retain their length and width while multiplying their upper frequency (4.87, 8.7, and 15.15 GHz) by the number of monopole profile steps (1, 2, and 3). The deviation is found mainly below 13% in relation to the reference formula. The concept of angular range based on pattern stability factor (PSF) is introduced to compare the solid angle of UWB pattern stability operation when increasing the bandwidth. The angular range degradation versus impedance bandwidth improvement shows all the possible performance levels of the antennas. Thus, the design of UWB printed monopoles is approached from both points of view, i.e., impedance bandwidth and pattern stability.

Implementation Details and Safety Analysis of a Microcontroller-based SIL-4 Software Voter

This paper presents a microcontroller-based software voting process that complies with Safety Integrity Level-4 (SIL-4) requirements. The selected system architecture consists of a 2 out of 2 schema, in which one channel acts as Master and the other as Slave. Each redundant channel uses a microcontroller as central element. The present analysis demonstrates that this system fulfills SIL-4 requirements. Once the system architecture is detailed, the system overall functionality and the data flow are presented. Then, the microcontrollers internal architecture is explained, and the software voting process flow-diagram is discussed. Afterward, the resources of the microcontroller architecture that are used for the execution of each task involved in the software voting process (hardware-software interaction) are determined. Finally, a fault analysis is elaborated to demonstrate that the cases in which the safety requirements are compromised have a very small occurrence probability, i.e., the hazard rate of proposed voting is below 1E-9.

Characterization of the EM environment of railway spot communication systems

Trains require spot communication systems to be supervised and controlled. EM interferences in their vicinity could cause their malfunction. Nowadays, the electromagnetic environment of these systems is being researched, but it is not well characterized yet. One of the most relevant origin of these interferences are the electromagnetic fields generated by the train itself. This work presents the measured signals of the EM fields generated by the common mode currents in the traction system and by the contact discontinuities between the pantograph and the catenary. The EM environment analysis is focused on the frequency range of the ASFA and ERTMS BTM systems.

Design for test of a low power multi-standard GPS/GALILEO RF front-end

This contribution deals with the complete design of a multi-standard GPS/GALILEO front-end, from setting the specifications through to the complete characterization of the device. Special focus will be given to the design for test and the characterization of the design, as optimizing the time spent on this improves time-to-market for the product under development. The highly integrated, low power GPS/GALILEO front-end is designed with a low-IF architecture. The front-end exhibits a voltage gain of 103dB with a power consumption of 66mW from a 3V voltage supply and 38mW if the internal dual-gain LNA is switched OFF. The SSB noise figure of 3.7dB which makes it suitable for high sensitivity applications. Te implemented architecture allows 3 different configurations, adding flexibility to its future applications.